Platinum(II) diimine complexes of acetylides containing 7-azaindolyl and 2,2-dipyridylamino functional groups

Four Pt(II) diimine complexes containing acetylide ligands that are functionalized by 7-azaindolyl or 2,2 -dipyridylamino groups have been synthesized and fully characterized. Complexes 1 and 2 have the general formula Pt(bpy)(C(identical)C-C6H4-R)2 where bpy = 2,2ʹ-bipyridine, R =N-7-azaindolyl for 1 and 2,2ʹ-dipyridylamino for 2, while complexes 3 and 4 have the general formula Pt(phen)(C (identical)C-C6H4-R)2 where phen = 1, 10-phenanthroline, R =N-7-azaindolyl for 3 and 2,2ʹ-dipyridylamino for 4. The structures of 1 and 4 have been determined by single-crystal X-ray diffraction analysis. All four complexes display orange or green emission when irradiated by UV light at ambient temperature. The emission energy of 2 and 4 in solution is concentration-dependent, attributable to excimer formation at high concentrations. The utility of the 2,2ʹ-dipyridylamino functions groups in complexes 2 and 4 was demonstrated by the interaction of 2 with Zn(II) ions via the dipyridyl chelating site, that leads to a change in emission intensity.